Method for preparing detergent compositions



United States Patent 3,247,113 METHQD FOR PREPARING DETERGENTCOMPUSKTIONS Raymond G. Matthaei, Fair Lawn, NJL, assignor to Leverfiqrothers Company, New York, N.Y., a corporation of tune No Drawing.Filed Feb. 25, 11953, Ser. No. 260,907 6 Claims. (Cl. 252-99) Thisinvention relates to a method of preparing detergent compositions andmore particularly to the manufacture of chlorinated detergents eminentlysuited for dishwashing purposes.

In U.S. Patent No. 2,689,225 there is disclosed detergent compositionscontaining as essential ingredients chlorinated trisodium phosphate, analkaline condensed phosphate such as sodium tripolyphosphate and analkaline detergent salt such as sodium silicate. These compositions weresaid to be particularly eincacious in cleansing stained dinnerware.

According to U.S. Patent No. 2,895,916, compositions of theaforementioned type are well-suited for use in automatic dishwashingmachines. The inventive feature in this patent was in a process forpreparing these detergent compositions which yielded products free ofthe undesirable characteristics of caking during storage and forming agel or gum in use. According to the patentees, these undesirablecharacteristics can only be eliminated by a critical procedure whichinvolves adding water and a. water-soluble allcali metal silicate to ananhydrous, water-soluble alkali metal condensed phosphate tosubstantially hydrate the phosphate before the addition of anychlorinated trisodium phosphate] to the mixture. The resultingagglomerates are then aged by agitation in a mixer for periods rangingfrom about 15 minutes to about 2 hours.

It has still not been possible, however, to manufacture a product ofthis composition exhibiting the following advantages: (1) sufiicientmoisture to avoid the high and possibly hazardous heat of hydration ofanhydrous products; (2) the ability to retain its available chlorine ata high level; (3) an acceptable odor; and (4) the ability to remainfreedlowing during shipping, during storage and after being opened. Acomposition having these attributes would be an extremely desirablecommodity.

An object of this invention is to provide detergent compositionscontaining chlorinated trisodium phosphate which are free from cakingduring storage and which do not form a gel or gum in use.

Another object is to provide a method for manufacturing chlorinateddishwashing detergents which contain suflicient moisture to avoid thehigh heat of hydration of anhydrous products, retain available chlorineat a high level, have an acceptable odor and remain free-flowing duringshipping and storage and after being opened.

These and other objects and advantages of the present invention areattained by a process which consists primarily of spraying the liquidingredients of the composition on the dry ingredients followed by acritical aging step to be discussed in detail later on. The agglomerateddetergent product at the completion of the mixing operation is moist andwill cake if packaged immediately, and four to five hours or possiblelonger is generally necessary to age this material in a rotating drumexposed to ambient air conditions before the caking tendencies of theproduct are such that it can be packaged without calcing. This lengthyaging period requires the installation of additional processingequipment.

It has now been determined that the aging period can be reduced from anestimated four to five hours to approximately one hour by the aging stepof the invention which comprises passing heated air over theagglomerdlillld Patented Apr. 1%, 1966 ated granules while they aremixed in a rotating drum to expose maximum surface area of the granules.This aging feature insures that the product will not cake afterpackaging.

For a detailed description of the components which can be utilized inpreparing the detergent compositions of this invention, attention isdirected to the U.S. patents discussed above whose disclosures areincorporated herein by reference. In general, the chlorinated trisodiumphosphate ingredient (4(N33P04"11H20) -NaOCl) is preferably utilized inproportions of about 6% to about 25% based on the weight of the finalproduct. The al kali metal silicates including sodium and potassiumsilicate, are preferably employed within a range of about 8% to about20% based on the weight of the final dry product. The alkaline condensedphosphate which is preferably sodium or potassium tripolyphosphate isutilized in proportions of about 40% to about 65% based on the contentof the final dry product. Although anhydrous tripolyphosphate can beused, it is preferred to employ a mixture of anyhydrous and hydratedtripolyphosphates.

A non ionic detergent is advantageously included in the composition toprovide detergent properties. Suitable compounds include the Pluronicswhich are condensates of ethylene oxide with a hydrophobic base formedby condensing propylene oxide with propylene glycol in which theproportion of ethylene oxide ranges from about 0% to 10% (Flu-ronic L60), 10% to 20 (Piuronic L-61), 20% to 30% (Pluronic L-62), etc. Ofcourse, other non-ionic detergents which are wellknown in the art can beincoporated and the invention is not limited to any particular detergentso long as it provides detergent properties to the compositions. Thiscomponent is preferably used in proportions ranging up to about 10% byweight of the final product.

It is within the scope of the present invention to utilize ourconventional components which do not afiect the basic characteristics ofthe composition. Thus, ingredients such as colorants, fluroescent dyes,perfumes, soilsuspending agents like sodium carboxymethylcellulose,inert diluen-ts, etc. may be present.

In general, the process of the invention involves mixing an anhydrouscondensed phosphate with a small amount of Water and thereafter addingthe chlorinated tripolyphosphate to the mixture. An aqueous solution ofthe silicate ingredient is then sprayed onto the aforementioned mixture.If non-ionic surface-activc agents are to be included, these materialsare also added preferably in the form of an aqueous solution. Otheringredients such as dyes and perfumes in aqueous mixture are added atthis point. This procedure yields a hydrated product. Mixing iscontinued for a short period of time. The granulated material is thenscreened, added to an aging drum and conditioned by passing heated airthrough the drum at a temperature of about F. to 185 F. It is preferredthat the granules be treated for approximately one hour with air atabout F. to F. The granules are also preferably rotated while being agedso that the maximum surface area is exposed. It is also preferred thatthe granules be reduced to a particle size of at least 10 mesh beforeaging for optimum results.

It has been found that in order to obtain a product having an acceptabledensity and hardness and the other advantages described above, certainlimitations must be observed during processing of the formulations. Forexample, the maximum permissable temperature during the agglomerationprocess is about 128 F. The larger the batch, the longer is the mixingtime during agglomeration.

Moreover, the moisture level of the final product must be in the rangeof about 22-35%. If the moisture level is below about 22%, the densityof the product will be too low, the appearance of the particles will bejagged rather than spherical, and the particles will be more friablethan desired. At moisture levels above about 35%, the agglomerates willbecome too wet during formulation and the material will ball-up intolarger lumps requiring further processing to reduce the lumps to thedesired size. Consequently, proper aging conditions must be maintainedto insure that the moisture level of the product is within the desiredrange.

It has also been determined that from about 5 to about 13% of the freemoisture content of the unconditioned particles must be removed duringthe aging procedure if a saisfactory free-flowing product is to beobtained. Thus, even unaged products with a moisture level approximatelywithin the 22-35% range disclosed above should be properly conditionedin accordance with the principles of this invention to yield anacceptable material.

The silicate ratio (Na O:SiO- utilized is also a pertinent factor indetermining the characteristics of the product. It has been observedthat the use of the so-called dry or powdered type of silicate may causeballing when liquids are added to the mixture during agglomeration. Thisresults in the production of large amorphous lumps which require furtherprocessing to reduce the size of the particles and thereby obtain thedesired product. When liquid silicates (water solutions of sodiumsilicates having Na O:SiO ratios ranging from about 111.65 to about1:3.75) are used, it is desirable to control the water content withincertain limits to minimize or avoid the formation of large amorphousmasses.

The aging step of this process is vitally important if a product is tobe obtained which is free-flowing and has the other desirable attributesmentioned. By the aging treatment with heated air, the moisture contentof the product is maintained at an acceptable level. The aging step ofthe invention gives a greater control over the moisture content of theproduct since the amount of moisture removed during aging must becontrolled within the limits discussed. An unduly large loss of moisturewill result in a reduction of the density of the product, the particleswill become friable and break down into fines and the heat of solutionof the product will increase. If suflicient moisture is not removed, thecaking characteristics of the product will not be changed appreciablyand the product will not be free-flowing.

Another precaution must be observed during processing. Temperatures inexcess of about 120 F. while agglomerating may result in decompositionof the chlorinated trisodium phosphate.

The aging step conditions the product without appreciably affecting itsactive chlorine content. Therefore, it is a distinct advantage of theinvention that a sufficient level of available chlorine is maintained inthe product to insure the effective use thereof. A further advantage ofthe aging procedure is that the surfaces of the particles are polishedand the product is therefore more uniform in appearance.

Other means may be employed to effect conditioning of the particles. Theuse of drying ovens may cause the particles which are not on the surfaceto retain more moisture than the particles on the top layer. This couldresult in an inferior conditioning of the material and subsequent cakingof the product. However, equipment can be used to keep the granules inmotion while they are drying in the oven. The use of a fluidized bed tokeep the particles in motion while they are being heated is analternative embodiment.

The following examples illustrate the use of the method according to thepresent invention. It will be understood, however, that these examplesare included merely for purposes of illustration and are not intended tolimit the scope of the invention as described herein unless otherwisespecifically indicated.

EXAMPLE I A formulation processed in accordance with the method of theinvention is listed below in order of addition of the ingredients. Thedesignation TPP refers to pentasodium tripolyphosphate. The Pluronicswere identified above.

Lbs. per lbs.

Component (as used): of product TPP, granular, medium density, anhy- Inthe precedure, the powdered and granular pentasodium tripolyphosphatecomponents were added to the mixing drum and mixing Was commenced. Thewater was then sprayed onto the particles in motion. The pentasodiumtripolyphosphate hexahydrate and the chlorinated trisodium phosphatewere added to the drum and mixing was continued for about a three-minuteperiod. Premix No. 2, No. 3 and No. 4 were successively sprayed onto theparticles and mixing was continued for about 10 minutes. Theagglomerated material was passed over a 10 mesh shaker screen. Theover-sized particles were processed through a Stokes Granulator equippedwith a 10 mesh screen.

The two screened fractions were combined in a rotatable drum andconditioned by passing hot air through the drum for approximately onehour at a temperature of about 140-150 F. and at a rate of about 40cubic feet per minute. The granules were continuously tumbled during theoperation. The hot air was shut off and the perfume added to theparticles. Mixing was continued for about five minutes after theaddition of the perfume and the granules were screened through a 10 meshshaker screen and packaged. The product was free-lowing, had anacceptable odor and had a chlorine content within the desired level.

EXAMPLE II A composition was prepared containing essentially the sameingredients as in Example I With the following differences inproportions expressed in terms of weight of the final product: thegranular TPP was used in a proportion of 41.50%; the TPP hexahydrate ina proportion of about 2.50%; the chlorinated trisodium phosphate in anamount of about 10.56%; and the water in proportions of about 29.1246%.The first three values are expressed on an anhydrous basis. The balanceof the formula is the same as that described in Example I.

The processing was essentially the same as that utilized in Example I.The granular TPP was added to the mixing drum and about 1.5% water wassprayed on the particles. The maximum temperature during agglomerationwas about F. with a somewhat longer mixing time being used than thethree-minute period of Example I. The granules were conditioned bypassing hot air through the mixing drum at 150 F. and at the rate ofabout 40 cubic feet per minute for about one hour. The maximumtemperature of the batch during the addition of the perfume Was 105 F.and 95 F. after screening. Bulk density of the free-flowing product was0.91-0.95.

The data in Table I below Was collected during a number of conditioningruns in accordance with the principles of this invention. Conditioningtemperatures and air rates were varied considerably within the limitsdiscussed above. The air rate is not a critical factor but can be widely4. A process for preparing a dishwashing composition containing about40% to 65% of a Water-soluble, alkaline condensed phosphate, about 8% toof a water-soluble alkali metal silicate and about 6% to chlorinatedtrisodium phosphate which comprises: (a) adding water to substantiallyanhydrous pentasodium tripolyphosphate, (b) adding hydrated pentasodiumtripolyphosphate and chlorinated trisodium phosphate to the mix, (c)adding Table I Uneonditioned Product Inlet Air Conditioned Productoilllet 1r, Run No, Rel.

Mois- Ohlo- Temp., Rel. Rate Volume Mols- Chlo- Hum, ture, rine, CakingF. Hum (it/min.) (ftfi/rnin.) ture tine, Caking percent percent percentper- (1 hour), percent cent percent 30. 4 0. 65 Caked- 110 19 172 76 0.63 free-flowing 54 29. 8 0.67 do 147 15 90 39. 5 27. 7 0. 65 d0 52 29. 30. 65 do 181 10 80 35.1 26. 6 75 29. 2 0. 68 do 141 17 92 40. 6 27. 4 42varied depending upon a number of factors including the air temperature,size of the equipment, etc.

The relative humidity data in Table I show that moisture was removedfrom the product in association with the heated air passed over theparticles. A free-flowing material was obtained with substantially noloss in the chlorine content of the product.

It will occur to those skilled in the art that there are manymodifications to the invention as specifically described herein. It isintended to include all such modifications in the scope of the appendedclaims.

I claim:

1. A process for preparing a detergent composition containing awater-soluble, alkaline condensed phosphate, a water-soluble alkalimetal silicate and chlorinated trisodium phosphate which comprises: (a)mixing a hydrated, water-soluble, alkaline condensed phosphate withchlorinated trisodium phosphate, (b) adding subsequently water and thetotal amount of an alkali metal silicate having Na O:SiO ratios rangingfrom about 1:1.65 to about 1:3.75 to form agglomerates at a maximumtemperature of 120 F. and (c) aging the agglomerates by treating withhot air while agitating the particles to remove about 5% to about 13% offree moisture content to form a moisture level of 22-35 in the finalproduct therefrom.

2. The process of claim 1 wherein the alkaline condensed phosphate issodium tripolyphosphate.

3. The process of claim 1 wherein the temperature of the hot air duringaging is about 90 F. to 185 F.

subsequently an aqueous solution of the total amount of an alkali metalsilicate selected from the group consisting of sodium silicate andpotassium silicate having Na O:SiO

ratios ranging from about 121.65 to about 1:3.75 containing an amount upto about 10% of a non-ionic synthetic detergent, (d) continuingagitation until agglomerated particles are produced at a maximumtemperature of F., (e) reducing the particles to a size of about 10 meshand (f) passing hot air through the particles at a temperature of about90 F. to 185 F. while tumbling them to remove about 5% to about 13% offree moisture content to form a moisture level of about 22-35% in thefinal non-caking product therefrom.

5. A process according to claim 4 in which the hot air is passed throughthe tumbling particles at a temperature of about F. to F. for about onehour.

6. A process according to claim 4 wherein a mixture of powdered andgranular pentasodium tripolyphosphate is used in step (a).

References Cited by the Examiner UNITED STATES PATENTS 9/1954 Andersonet al. 25299 7/1959 Milenkevich et al. 25299

1. A PROCESS FOR PREPARING A DETERGENT COMPOSITION CONTAINING AWATER-SOLUBLE, ALKALINE CONDENSED PHOSPHATE, A WATER-SOLUBLE ALKALIMETAL SILICATE AND CHLORINATED TRISODIUM PHOSPHATE WHICH COMPRISES: (A)MIXING A HYDRATED, WATER-SOLUBLE, ALKALINE CONDENSED PHOSPHATE WITHCHLORINATED TRISODIUM PHOSPHATE, (B) ADDING SUBSEQUENTLY WATER AND THETOTAL AMOUNT OF AN ALKALI METAL SILICATE HAVING NA2O:SIO2 RATIOS RANGINGFROM ABOUT 1:1.65 TO ABOUT 1:3.75 TO FORM AGGLOMERATES AT A MAXIMUMTEMPERATURE OF 120*F. AND (C) AGING THE AGGLOMERATES BY TREATING WITHHOT AIR WHILE AGITATING THE PARTICLES TO REMOVE ABOUT 5% TO ABOUT 13% OFFREE MOISTURE CONTENT TO FORM A MOISTURE LEVEL OF 22-35% IN THE FINALPRODUCT THEREFROM.